System to assist in the release of a collapsible stent from a delivery device

ABSTRACT

A delivery device for an implantable medical device having a retention member at an end thereof may include a shaft extending in a longitudinal direction and defining a longitudinal axis, an elongated sheath surrounding a longitudinal portion of the shaft, a compartment defined inside the sheath and adapted to receive the medical device in an assembled condition, a retainer positioned at one end of the compartment, and an energy storage element positioned on the longitudinal portion of the shaft and configured to be radially compressed by the medical device when the elongated sheath covers the compartment containing the medical device. The sheath may be slidable relative to the shaft in the longitudinal direction. The retainer may include a recess adapted to receive the retention member of the medical device in the assembled condition.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.13/790,819, filed on Mar. 8, 2013, which claims the benefit of thefiling date of U.S. Provisional Patent Application No. 61/666,209, filedon Jun. 29, 2012, the disclosures of which are hereby incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention is related to prosthetic heart valve replacement,and more particularly to devices, systems, and methods for transcatheterdelivery of collapsible prosthetic heart valves.

Prosthetic heart valves that are collapsible to a relatively smallcircumferential size can be delivered into a patient less invasivelythan valves that are not collapsible. For example, a collapsible valvemay be delivered into a patient via a tube-like delivery apparatus suchas a catheter, a trocar, a laparoscopic instrument, or the like. Thiscollapsibility can avoid the need for a more invasive procedure such asfull open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valvestructure mounted on a stent. There are two types of stents on whichcollapsible valves are mounted: a self-expanding stent and aballoon-expandable stent. To place a collapsible valve into a deliveryapparatus and ultimately into a patient, the valve must first becollapsed or crimped to reduce its circumferential size.

When a collapsed valve has reached the desired implant site in thepatient (e.g., at or near the annulus of the patient's heart valve thatis to be replaced by the prosthetic valve), the prosthetic valve can bereleased from the delivery apparatus and re-expanded to full operatingsize.

Despite the various improvements that have been made to the collapsibleprosthetic heart valve delivery process, conventional delivery devices,systems, and methods suffer from some shortcomings. For example, theself-expanding collapsible valve may be held in a catheter by stentretention members that are inserted into the retainer portion of thecatheter. During deployment of the self-expanding valve into the desiredarea (e.g., the aortic valve annulus), the delivery process may causethe stent to become twisted relative to the retainer portion of thecatheter, which may make it difficult to release the valve because thestent retention members may catch on the retainer during deployment.

There therefore is a need for further improvements to the devices,systems, and methods for transcatheter delivery of collapsibleprosthetic heart valves. Among other advantages, the present inventionmay address one or more of these shortcomings.

BRIEF SUMMARY OF THE INVENTION

Delivery devices for a collapsible prosthetic heart valve and methods ofdelivering a collapsible prosthetic heart valve using same are aspectsof the invention. In addition, any device having one or more of thefollowing features and used in the transcatheter delivery of acollapsible heart valve are specific aspects of the invention.

A delivery device for an implantable medical device having a retentionmember at an end thereof may include a shaft extending in a longitudinaldirection and defining a longitudinal axis, an elongated sheathsurrounding a longitudinal portion of the shaft, a compartment definedinside the sheath and adapted to receive the medical device in anassembled condition, a retainer positioned at one end of thecompartment, and an energy storage element positioned on thelongitudinal portion of the shaft and configured to be radiallycompressed by the medical device when the elongated sheath covers thecompartment containing the medical device. The sheath may be slidablerelative to the shaft in the longitudinal direction. The retainer mayinclude a recess adapted to receive the retention member of the medicaldevice in the assembled condition.

The energy storage element may be at least partially aligned with therecess in a circumferential direction about the longitudinal axis. Theenergy storage element may be an elastomeric element surrounding atleast a part of the longitudinal portion of the shaft. A surface of theelastomeric element may have a plurality of raised portions and aplurality of lowered portions distributed in a circumferential directionabout the longitudinal axis. The implantable medical device may have aplurality of retention members at the end thereof and the retainer mayinclude a plurality of recesses each adapted to receive a correspondingone of the retention members. Each of the raised portions of theelastomeric element may be at least partially aligned with acorresponding one of the recesses in the circumferential direction.

Each of the lowered portions of the elastomeric element may be disposedbetween two adjacent ones of the raised portions in the circumferentialdirection. The elastomeric element may be formed from a materialselected from the group consisting of silicone, urethane, nylon, pebax,santoprene, butyl, neoprene, and combinations thereof. The elastomericelement may extend along the shaft in the longitudinal directionthroughout the entire length of the compartment. The energy storageelement may include a leaf spring attached to the shaft. The leaf springmay extend in a circumferential direction about the longitudinal axisaround at least a part of the longitudinal portion of the shaft.

The energy storage element may include a plurality of leaf springsdistributed about the shaft in a circumferential direction about thelongitudinal axis. Each of the leaf springs may extend in thelongitudinal direction along at least a part of the longitudinal portionof the shaft. The energy storage element may be a recess insert, therecess insert overlying a bottom surface of the recess. The recessinsert may be a pad of elastomeric material. The recess insert may be aspring.

A method of prosthetic valve delivery may include providing anexpandable prosthetic valve having a retention member at an end thereofand loading the valve into a compartment of a delivery device. Thedelivery device may include a shaft, an elongated sheath surrounding alongitudinal portion of the shaft and slidable in longitudinaldirections relative to the shaft, an energy storage element positionedon the longitudinal portion of the shaft, a retainer positioned at oneend of the compartment, and a recess in the retainer. The valve may beloaded into the compartment with the retention member positioned in therecess and with the valve overlying at least a portion of the energystorage element.

The method may also include sliding the sheath in a first one of thelongitudinal directions over the valve to radially compress the energystorage element and to hold the energy storage element in a compressedcondition. The method may also include inserting the delivery device ina patient to position the valve at a target location and sliding thesheath in a second one of the longitudinal directions to uncover thevalve. The energy storage element may be released from the compressedcondition and may radially expand to impart an outward radial force tothe valve. The energy storage element may be an elastomeric elementsurrounding at least a part of the longitudinal portion of the shaft.The energy storage element may include a leaf spring attached to theshaft. The energy storage element may be a recess insert, the recessinsert overlying a bottom surface of the recess.

Another delivery device for an implantable medical device having aretention member at an end thereof may include a shaft extending in alongitudinal direction and defining a longitudinal axis, an elongatedsheath surrounding a longitudinal portion of the shaft, a compartmentdefined inside the sheath and adapted to receive the medical device inan assembled condition, a retainer positioned at one end of thecompartment, and a balloon extending along at least part of thelongitudinal portion of the shaft. The sheath may be slidable relativeto the shaft in the longitudinal direction.

The retainer may include a recess adapted to receive the retentionmember of the medical device in the assembled condition. The recess mayhave a bottom surface located a first distance from the longitudinalaxis. The balloon may have a deflated state in which an outer surface ofthe balloon is located a second distance from the longitudinal axis, thesecond distance being less than the first distance. The balloon may havean inflated state in which the outer surface of the balloon is located athird distance from the longitudinal axis, the third distance beinggreater than the first distance.

Yet another delivery device for an implantable medical device having aretention member at an end thereof may include a shaft extending in alongitudinal direction and defining a longitudinal axis, an elongatedsheath surrounding a longitudinal portion of the shaft, a compartmentdefined inside the sheath and adapted to receive the medical device inan assembled condition, and a retainer positioned at one end of thecompartment. The retention member may have an angled lateral edge. Thesheath may be slidable relative to the shaft in the longitudinaldirection.

The retainer may include a recess adapted to receive the retentionmember of the medical device in the assembled condition. The retainermay have a retention edge facing the compartment. The recess may have afirst region sized to receive the retention member. The recess mayinclude a protuberance defining both a narrowed neck between the firstregion and the retention edge and an angled sidewall of the firstregion. In the assembled condition, an angle formed between the angledsidewall and the longitudinal axis may be greater than an angle formedbetween the angled lateral edge and the longitudinal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be discussed withreference to the appended drawings. It is appreciated that thesedrawings depict only some embodiments of the invention and are thereforenot to be considered limiting of its scope.

FIG. 1A is a side view of a transfemoral delivery device for acollapsible prosthetic heart valve;

FIG. 1B is a longitudinal cross-section of a retainer of a deliverydevice depicted in FIG. 1A, shown without the proximal conical end orthe distal sheath;

FIG. 1C is one embodiment of a collapsible prosthetic heart valve thatcan be delivered with the device of FIG. 1A;

FIG. 2 is a side view of a transapical delivery device for a collapsibleprosthetic heart valve;

FIG. 3A is a side view of a transfemoral delivery device including anelastomeric element;

FIG. 3B is an enlarged side view of a portion of the device of FIG. 3A;

FIG. 3C is an enlarged perspective view of a portion of the device ofFIG. 3A;

FIG. 3D is a longitudinal cross-section of the device of FIG. 3C;

FIG. 3E is a side view of a transfemoral delivery device including analternative elastomeric element running along a relatively greaterlength of the component;

FIG. 4A is a side view of another embodiment of a retainer suitable foruse in the delivery device of FIGS. 1A and 2;

FIG. 4B is a side view of another embodiment of a retainer suitable foruse in the delivery device of FIGS. 1A and 2;

FIG. 5A is a side view of a portion of a transfemoral delivery deviceincluding a balloon;

FIG. 5B is an end view of a portion of the device of FIG. 5A;

FIG. 6A is a side view of another embodiment of a retainer suitable foruse in the delivery device of FIGS. 1A and 2;

FIG. 6B is a side view of another embodiment of a retainer suitable foruse in the delivery device of FIGS. 1A and 2;

FIG. 7A is a side view of a transfemoral delivery device including acoiled spring attached to the inner shaft;

FIG. 7B is an end view of a portion of the device of FIG. 7A;

FIG. 7C is an end view of a device that is a variation of the device ofFIG. 7A;

FIG. 7D is a side view of a transfemoral delivery device including leafsprings attached to the inner shaft;

FIG. 8A is a side perspective view of an alternative embodiment of avalve retainer; and

FIG. 8B is a side view of another embodiment of a valve retainer.

DETAILED DESCRIPTION

As used herein, the terms “proximal” and “distal” are to be taken asrelative to a surgeon using the disclosed delivery devices. “Proximal”is to be understood as relatively close to the surgeon and “distal” isto be understood as relatively farther away from the surgeon.

Referring now to FIGS. 1A, 1B, and 1C to illustrate the structure andfunction of the present invention, a first embodiment of a deliverydevice 10 has a distal tip 12 and a catheter assembly 14 extending fromthe distal tip to a proximal end (not shown) that includes a handle (notshown) for a user to control the delivery device 10. The delivery device10 is an exemplary transfemoral delivery device for a collapsibleprosthetic heart valve. Examples of handles that can be used to controldeployment of the delivery device 10 are shown and described in U.S.Patent Application Publication No. 2012/0123528, which is herebyincorporated by reference herein.

The catheter assembly 14 includes a distal sheath 22 extending from thehandle towards the distal tip 12, a hollow inner shaft 24 located insideof the distal sheath and extending from the handle to the distal tip,and a valve receiving compartment 28 configured to receive a collapsibleprosthetic heart valve or other implantable device, such as the valve 11shown in FIG. 1C, for delivery inside of a patient. The valve 11 mayhave a stent portion 1 that includes a plurality of stent struts 2 thatdefine cells 3 therebetween. At least one retention member 4 may extendfrom an end of the stent portion 1. The valve 11 may also have a valveportion 5 stitched or otherwise attached to the stent portion 1.

The valve receiving compartment 28 includes a retainer 30 located, inthis embodiment, inside the distal sheath 22, a proximal conical end 31adjacent the retainer 30, and a distal conical end 32 spaced from theretainer 30. The conical end 32 is joined to the inner shaft 24 at oneend of the valve receiving compartment 28, and the conical end 31 andthe retainer 30 are joined to a stiffening member 25 mounted on theinner shaft 24 at the other end of the valve receiving compartment 28.Preferably, the inner shaft 24 and the stiffening member 25 have thesame internal diameter, adapted to receive a guide wire (not shown).Alternatively, in any of the delivery device embodiments describedherein, the inner shaft 24 and the stiffening member 25 may be a singleunitary shaft.

The retainer 30 may define one or more recesses 36, each recess beinglocated at or adjacent the retention edge 34 of the retainer andconfigured to receive a corresponding retention member 4 of the stentportion 1 of the collapsible valve 11. For delivery into a patient, thecollapsible valve 11 is loaded into the valve receiving compartment 28around the inner shaft 24 and between conical ends 31 and 32, and thestent portion 1 of the valve is coupled to the retainer 30 while placingat least one retention member 4 into at least one recess 36.

Regardless of whether a valve 11 is to be delivered transfemorally intoa patient to replace a native valve (e.g., the patient's aortic valve,mitral valve, etc.) using a device such as the device 10 shown in FIG.1A, or transapically using a device such as the device 10′ describedbelow with respect to FIG. 2, the stent portion 1 of the valve 11preferably is attached to the retainer 30, 30′ by the retention members4 protruding from the end of the stent that is opposite the end at whichthe valve is located (i.e., the retention members protrude from theaortic side of the stent). Preferably, the retention members 4 arepositioned at the end of the valve 11 that is to be deployed last, i.e.,the end of the valve that will be covered by the distal sheath thelongest.

For example, in a transfemoral prosthetic aortic valve delivery device(e.g., the device 10 shown in FIG. 1A), the retention edge 34 of theretainer 30 is located at the distal end thereof, and the sheath 22 ismoved in a proximal direction to unsheathe and deploy the valve, withthe distal end of the valve unsheathed first.

The retention edge 34 of the retainer 30 may have a chamfered outeredge, which may help reduce frictional forces acting between the sheath22 and the retainer during unsheathing and resheathing of a stent. Theretention edge of any of the retainer embodiments disclosed herein mayhave chamfered outer edges.

Each recess 36 may have a similar shape and a slightly larger size thanthe stent retention member 4 so as to capture same readily, but withonly a small amount of relief therebetween. Forming recesses 36 with anappropriate shape and size may prevent longitudinal movement of thevalve within the valve the receiving compartment 28, such as duringdeployment or resheathing procedures.

In other embodiments, the retainer 30 may be configured such that therecesses 36 are rotatable relative to the inner shaft 24, for example,as shown and described in United States Patent Application PublicationNo. 2012/0078350, which is hereby incorporated by reference herein.

To load the delivery device 10 with a collapsible prosthetic valve 11, auser attaches the stent portion 1 of the prosthetic valve into thecompartment 28 and to the retainer 30, compressing or crimping the valveuntil it fits inside the distal sheath 22, which holds the valve in acompressed state until the user decides to deploy the valve. When thevalve 11 is later deployed by unsheathing, the stent portion 1self-expands and is ultimately disengaged from the delivery device 10once the retention members 4 are released from the retainer 30. If thevalve 11 has not been fully deployed, i.e., if a portion of the valveremains in a collapsed state beneath the distal sheath 22, the valve maybe resheathed by sliding the distal sheath back over the portion of thestent that has expanded, thereby recollapsing the expanded portion ofthe stent.

Referring to FIG. 2, a second embodiment of a delivery device 10′ has adistal tip 12 and a catheter assembly 14′ extending from the distal tipto a proximal end (not shown) that may include a handle (not shown) fora user to control the delivery device 10′. The delivery device 10′ is anexemplary transapical delivery device for a collapsible prosthetic heartvalve.

The catheter assembly 14′ may include a proximal sheath 20 extendingfrom the handle towards the distal tip 12, a distal sheath 22′ extendingfrom the distal tip 12 towards the handle, a hollow tube 26 that extendsslidably from the proximal end through the proximal sheath 20 andattaches to the distal sheath 22′ at the distal tip 12 of the deliverydevice 10′, and a valve receiving compartment 28′ configured to receivea collapsible prosthetic valve, such as the valve 11 shown in FIG. 1C,for delivery inside of a patient.

The valve receiving compartment 28′ is configured to receive acollapsible prosthetic heart valve such as the valve 11. The valvereceiving compartment 28′ includes a proximal conical end 31′ at thedistal end of the proximal sheath 20, a distal conical end 32′ spacedfrom the proximal conical end, and a retainer 30′ located, in thisembodiment, adjacent the distal conical end 32′ and inside the distalsheath 22′. A hollow inner shaft 24′ is connected at one end to theproximal conical end 31′ and at the other end to the distal conical end32′, and slidably receives the hollow tube 26 therethrough. For deliveryinto a patient, a collapsible valve 11 is loaded into the valvereceiving compartment 28′ around the inner shaft 24′ and between theconical ends 31′ and 32′, and the stent portion of the valve is coupledto the retainer 30′.

The retainer 30′ may be the same as the retainer 30 shown and describedabove, but with a sufficient central bore extending longitudinallytherethrough to permit the hollow tube 26 to be slidably receivedtherethrough.

As can be seen in FIG. 2, in a transapical prosthetic aortic valvedelivery device such as the device 10′, the retention edge 34 is locatedat the proximal end of the retainer 30′, and the distal sheath 22′ ismoved in a distal direction to unsheathe and deploy the valve, with theproximal end of the valve unsheathed first.

The retainers, elastomeric elements, and/or springs described below canbe used in either the transfemoral or the transapical delivery devices10 and 10′ described above with respect to FIGS. 1A, 1B, and 2. Also,the inventive retainers, elastomeric elements, and springs shown anddescribed in this application may be configured to be used with othertypes of tube-like delivery devices for collapsible implantable devices.However, for convenience, the retainers, elastomeric elements, andsprings will be described with respect to the transfemoral device 10. Inthis aspect of the invention, the delivery device is provided with atleast one member (e.g., an elastomeric element or spring) uniquelysuited to assist in the rapid and smooth ejection of the implantabledevice from the delivery device when desired. This member can provide aforce against at least one portion of the stent, urging that portion todisengage from the delivery device.

Referring to FIGS. 3A-3D, the device 10 may include an elastomericelement 40 disposed or situated over at least a portion of the innershaft 24 and optionally attached to a distal portion of the retainer 30.When the heart valve 11 is assembled or fitted to the retainer 30 suchthat the retention members 4 are engaged with the recesses 36 and thedistal sheath 22 is covering the compartment 28 containing the valve,the elastomeric element 40 is adapted to be under radial compressionfrom the stent and sheath, such that when the distal sheath is removedfrom the compartment, the stored energy within the elastomeric insertpushes radially outwardly against the stent, thereby assisting theremoval of the retention members from the corresponding recesses 36 andassisting in the separation of the valve from the delivery device 10.

The elastomeric element 40 may include a proximal portion 41 adjacentthe retention edge 34 of the retainer 30 and a distal portion 42 thatextends from the proximal portion at least a portion of the distancetowards the distal end of the compartment 28. As shown in FIGS. 3A-3D,the diameter of the elastomeric element 40 may taper from a firstdiameter D1 at the proximal portion 41 to a second diameter D2 at thedistal portion 42. One or more of the proximal portion 41 and the distalportion 42 may also taper within the respective portion. For example,the distal portion 42 may taper from a wider diameter adjacent theproximal portion 41 to a smaller diameter remote from the proximalportion. In other embodiments (not shown), the proximal portion 41 andthe distal portion 42 may have the same diameter, or the distal portionmay have a greater diameter than the proximal portion.

The elastomeric element 40 may have a plurality of raised portions 43and lowered portions 44, the raised and lowered portions alternatingaround the circumference of the elastomeric element such that the raisedportions are oriented at the same circumferential locations as therecesses 36. The raised portions 43 may extend a first radial distanceR1 from the longitudinal axis L of the retainer 30, and the loweredportions 44 may extend a second radial distance R2 from the longitudinalaxis L, the first radial distance being greater than the second radialdistance. The bottom surface 50 of the recess 36 may be located a thirdradial distance R3 from the longitudinal axis L of the retainer 30, thethird radial distance being less than the first radial distance. In someembodiments, as shown in FIG. 3D, the third radial distance R3 may beless than both the first and second radial distances R1 and R2.

By having the raised portions 43 that are circumferentially aligned withthe recesses 36 extend to a greater radial distance from thelongitudinal axis L than the bottom surface 50, the proximal portion 41of the elastomeric element 40 will be partially radially compressed atleast at the locations of the raised portions, thereby storing energy,when the retention elements 4 are pushed against the bottom surface 50of the recess when the distal sheath 22 is covering the elastomericelement, the valve 11, and the retainer 30.

By having the lowered portions 44 extend to a lesser radial distancefrom the longitudinal axis L than the raised portions 43, the width in aradial direction of the retention edge 34 of the retainer 30 will begreater at locations circumferentially separated from the recesses 36than the width of the retention edge at or adjacent the recesses. Sincethe stent struts 2 that do not have retention members 4 may abut theretention edge 34 when the valve 11 is loaded into the device 10, such aconfiguration having lowered portions 44 may permit easier loading ofthe valve into the device, because the stent struts that do not haveretention members will have a greater surface of the retention edge tocontact during the loading process, reducing the chance that such stentstruts will slip off the retention edge during loading of the valve.

It is not required that the proximal portion 41 have raised portions andlowered portions; the proximal portion may have a surface located at asingle radial distance around the circumference of the elastomericelement. However, it is preferred that such a single radial distance begreater than the third radial distance R3 at which the bottom surface 50of the recess 36 is located, so that the proximal portion 41 of theelastomeric element 40 will be partially radially compressed when thedistal sheath 22 pushes the retention elements 4 against the bottomsurface 50 of the recess 36.

The elastomeric element 40 may also have an optional alignment featurein the form of a slot 45 within each of the raised portions 43 that isaligned with the center of the corresponding recess 36. As shown inFIGS. 3A-3D, the alignment feature is in the form of a slot 45 that isrecessed below the surface of the corresponding raised portion 43.However, the alignment feature may alternatively be in the form of araised rib that is adapted to fit into a cell 3 between adjacent stentstruts 2, or it may be in the form of a marking or indicia that isneither raised nor lowered with respect to the surface of the raisedportion 43. The alignment feature, regardless of whether it is a slit, arib, or a surface marking or indicia, may also be in an indicative shapesuch as a letter, number, arrow, or the like.

The retainer 30 may include a circumferential groove 33 (FIG. 3D)adjacent the retention edge 34 that is adapted to receive acorresponding circumferential rib 49 of the elastomeric element 40during assembly of the elastomeric insert to the retainer 30. As shownin FIG. 3D, the circumferential rib 49 is located in the proximalportion 41 of the elastomeric element 40, but that need not be the case.In other embodiments (not shown), the elastomeric element 40 may includea circumferential rib in the distal portion 42 thereof, and thecircumferential rib may be adapted to be received in a correspondingcircumferential groove in the inner shaft 24. In other embodiments,other conventional interlocking mechanisms may be used to couple theelastomeric element 40 to the inner shaft 24 and/or the retainer 30,such as a plurality of grooves disposed on a tapered distal portion ofthe retainer interlocking with a plurality of ribs located in a taperedinner lumen of the elastomeric element. The elastomeric element 40 mayalso be glued or affixed to the inner shaft 24 and/or the retainer 30 inany conventional manner.

It is contemplated that multiple variants of the elastomeric element 40may be provided. For example, as shown in FIG. 3E, the elastomericelement 40′ may extend the entire length of the compartment 28 to assistin the radial expansion and/or release of the entire valve. In otherembodiments, a plurality of smaller elements of varying diameter andcomposition may be used at different locations within the compartment.The amount of force that can be exerted will depend upon, for example,the elastomeric material used, its density and elasticity, its thicknessand dimensions, and the degree that it is compressed by the valve 11once the distal sheath 24 is slid over the compartment 28. Suitablematerials for the elastomeric element 40 include, for example, silicone,urethane, nylon, pebax, santoprene, butyl, neoprene, or a combinationthereof. In one example, a plurality of spaced-apart energy storageelements made of an elastomer or another energy storage material may bedistributed about the inner shaft 24 in a circumferential directionperpendicular to the longitudinal direction L (e.g., in theconfiguration shown in FIG. 7D).

Alternatively, or in combination with the elastomeric element 40 or 40′,one or more of the recesses 36 may include an elastomeric materialtherein to assist in ejecting the retention members therefrom.

For example, as shown in FIG. 4A, one or more of the recesses 36 mayeach define a bottom surface 50, and a pad or section of an elastomericmaterial, as described above for the elastomeric element 40, in the formof an elastomeric insert 55 may be deposited into the recess overlyingthe bottom surface. The elastomeric insert 55 may be attached to thebottom surface 50 in numerous ways, including, for example, an adhesivematerial. In a particular example, all of the recesses 36 may include anelastomeric insert 55 therein.

The elastomeric insert 55 can have a planar upper surface 58 that has acontour that conforms to the contour of the bottom surface 50 of therecess 36, or alternatively, the elastomeric insert may have an uppersurface that has a contour that does not conform to the contour of thebottom surface of the recess. In one example of an upper surface 58 thatis conformal to the bottom surface 50, the upper surface may be convexlycurved in a direction around the longitudinal axis of the inner shaft24, such that the upper surface of each of the elastomeric inserts formsa portion of a cylinder.

As shown in FIG. 4B, in an alternative embodiment of the elastomericinsert 55 shown in FIG. 4A, an elastomeric insert 55′ may be attached tothe bottom surface 50 by interlocking of a prong 56 into a recess 51extending into the retainer 30 from the bottom surface of the recess 36.The prong 56 can have one or more tabs 57 that extend from the prong ina direction that is transverse to the longitudinal axis of the prong,and the tabs can be adapted to fit into corresponding notches 52extending in a direction that is transverse to the longitudinal axis ofthe recess 51.

In another alternative embodiment of the elastomeric insert 55 shown inFIG. 4A, one or more of the recesses 36 may each be partially orcompletely lined with an elastomeric layer that may be conformally ornon-conformally deposited within the recess. Such an elastomeric layermay extend only across the bottom surface 50 of the recess, or it mayextend across the bottom surface and sidewalls 53 of the recess thatextend from the bottom surface in a direction that is transverse to aplane of the bottom surface.

Still further, the retainer 30 may itself be formed from an elastomericmaterial so as to slightly compress when covered by the distal sheath22, but then radially expand when exposed, thereby facilitating therelease of the retention members therefrom.

Alternatively, or in combination with the elastomeric element 40 or 40′,the device 10 may include a balloon to assist in ejecting the retentionmembers therefrom. Rather than using an elastomeric material, theelastomeric elements 40 and 40′ and all variants thereof (e.g., theelastomeric inserts 55, 55′ of FIGS. 4A and 4B) may be fashioned from aballoon that will exert an outward radial force when no longerconstrained by the distal sheath 22 and inflated, and thereby help ejectthe retention members from the recesses 36.

For example, as shown in FIGS. 5A and 5B, the insert 40 can be replacedwith a balloon assembly 80 having a plurality of lobes 81 attached toand extending around the inner shaft 24 for a portion of or the entirelength of the compartment 28. Each of the lobes 81 may be in fluidcommunication with one or more inflation lumens 82 each extendingbetween a proximal end of the device 10 (not shown) and one or more ofthe lobes. As shown in FIG. 5B, each of the lobes 81 may be suppliedwith fluid by a corresponding inflation lumen 82. Alternatively, asingle inflation lumen may be in fluid communication with all of thelobes 81, or a plurality of inflation lumens may be in fluidcommunication with each of the lobes.

As shown in FIG. 5B, the balloon assembly 80 may have three lobes 81,each lobe circumferentially aligned with a corresponding one of therecesses 36. Alternatively, the balloon assembly 80 may have a singlelobe extending around a portion of or all of the circumference of theinner shaft 24, or the balloon assembly may have any other number oflobes, including for example, one, two, four, six, eight, or nine.However, it is preferred that the number of lobes be equal to the numberof recesses.

Similar to the raised portions 43 of the elastomeric element 40described above, the lobes 81 of the balloon assembly 80, when inflated,may each extend a first radial distance R1 from the longitudinal axis Lof the retainer 30, and the bottom surface 50 of the recess 36 may belocated a third radial distance R3 from the longitudinal axis L of theretainer 30, the third radial distance being less than the first radialdistance.

By having the lobes 81 that are circumferentially aligned with therecesses 36 extend to a greater radial distance from the longitudinalaxis L than the bottom surface 50, the lobes can be inflated to asufficient radius to contact the stent struts 2 having retentionelements 4, thereby facilitating the release of the retention membersfrom the recesses 36.

The valve 11 may be loaded into the device 10 when the lobes 81 aredeflated (i.e., without a substantial amount of fluid therein), so thatthe space within the compartment 28 occupied by the lobes may beminimized during insertion of the distal portion of the device into apatient.

When the distal sheath 22 is moved to uncover the compartment 28, afluid (e.g., a liquid such as saline, a gas such as air, etc.) may beselectively flowed into lobes 81 by the user to inflate the lobes. Eachof the lobes 81, when inflated, may exert an outward radial forceagainst the stent portion 1 of the valve 11, or, more specifically,against the stent struts 2 having retention members 4 attached thereto,so that the lobes may contact and push the stent radially outward,thereby facilitating the release of the retention members 4 from therecesses 36.

Although not shown in the figures, aspects of the elastomeric elementand balloon-based embodiments may be combined into a single embodiment.For example, portions of the elastomeric element 40, e.g., the raisedportions 43, may be replaced by balloon lobes that can be selectivelyinflated to facilitate the release of the retention members 4 from therecesses 36.

Rather than using an elastomeric material or a balloon, the elastomericelements 40 and 40′, the balloon assembly 80, and all variants thereof(e.g., the elastomeric inserts 55, 55′ of FIGS. 4A and 4B) may befashioned from a compression spring, spring steel, shape memorymaterial, and the like that will exert an outward radial force when nolonger constrained by the distal sheath 22, and thereby help eject theretention members from the recesses 36.

For example, as shown in FIGS. 6A and 6B, one or more of the recesses 36may include a spring in the form of a leaf spring 60 (FIG. 6A), a coilspring 62 (FIG. 6B), or any other conventional configuration thereinthat is biased to exert an outward radial force when a retention member4 is pushed radially inward against it by the distal sheath 22 when thedistal sheath is covering the compartment 28. When the distal sheath 22is moved to uncover the compartment 28, the stored energy in the spring60 or 62 may be released, and the spring may push the retention memberradially outward, thereby facilitating the release of the retentionmembers from the recesses 36.

The leaf spring 60 shown in FIG. 6A may be attached to the bottomsurface 50 or one of the sidewalls 53 of the recess 36. As shown, theleaf spring 60 is attached to a portion of the bottom surface 50adjacent the narrowed neck portion 38. The coil spring 62 shown in FIG.6B may be attached to the bottom surface 50, one of the sidewalls 53, ora recess 59 extending below the bottom surface of the recess 36. Asshown, the coil spring 62 is attached to a surface of a recess 59extending below the bottom surface 50 of the recess 36.

In other examples, as shown in FIGS. 7A-7D, the insert 40 can bereplaced with a spring in the form of a single coiled leaf spring 70attached to and extending around the inner shaft 24 (FIGS. 7A and 7B), aplurality of curved leaf springs 71 each attached to and extendingpartially around the inner shaft 24 (FIG. 7C), or one or more straightor curved leaf springs 72 attached to the inner shaft and extending inthe longitudinal direction of the inner shaft (FIG. 7D) for part or theentire length of the compartment 28.

Each of the leaf springs 70, 71, and 72 may be biased to exert anoutward radial force when the stent portion 1 of the valve 11 is pushedradially inward against it by the distal sheath 22 when the distalsheath is covering the compartment 28. When the distal sheath 22 ismoved to uncover the compartment 28, the stored energy in the springs 70or 72 may be released, and the springs may push the stent radiallyoutward, thereby facilitating the release of the retention members 4form the recesses 36.

The coiled leaf spring 70 shown in FIGS. 7A and 7B may be attached tothe inner shaft 24 and may extend around the inner shaft for any portionof the circumference of the inner shaft. For example, as shown, a singlecoiled leaf spring 70 extends 1080° (three times) around the inner shaft24. In other embodiments, a coiled leaf spring can extend any number oftimes around the inner shaft 24, including once or twice. Alternatively,as shown in FIG. 7C, a plurality of curved leaf springs 71 can extendaround a portion of the circumference of the inner shaft 24, such as twoleaf springs each extending around 180° (half) of the circumference ofthe inner shaft 24.

As shown in FIG. 7D, or one or more straight or curved leaf springs 72may attached to the inner shaft 24 and may extend in the longitudinaldirection of the inner shaft for part or the entire length of thecompartment 28. There may be a plurality of springs 72 attached to theinner shaft at a plurality of respective circumferential locationsaround the inner shaft 24, such that each spring is circumferentiallyaligned with a corresponding one of the recesses 36. However, in otherembodiments, there may be more or less springs 72 than recesses. In oneexample, there may be six circumferentially spaced springs 72 and threerecesses 36, so that every other spring is circumferentially alignedwith a corresponding recess, and the remaining springs are locatedbetween adjacent ones of the recesses. Similar to raised portions 43 andthe lobes 81 described above, the springs 72 that are circumferentiallyaligned with the recesses 36 may be biased to extend to a greater radialdistance from the longitudinal axis of the retainer 30 than the bottomsurface 50, so that when the distal sheath 22 is withdrawn from thevalve, the springs may contact the stent struts 2 having retentionelements 4, thereby facilitating the release of the retention membersfrom the recesses 36.

It is to be understood that many of the energy storage elementsdescribed herein, such as the elastomeric materials extending around theinner shaft 24 and extending within the recesses 36, and the springsextending around the inner shaft and extending within the recesses, canbe combined with one another in a single device. For example, theelastomeric element 40 can extend around the inner shaft 24, while theleaf springs 60 can be disposed in corresponding ones of the recesses36. Any combination of the embodiments described above can be used in asingle device.

As the delivery devices described herein are advanced into a patient,such as through the femoral artery towards the aorta, the stent portion1 of the prosthetic valve 11 may become twisted about its longitudinalaxis relative to the retainer due to the maneuvering of the deliverydevice through the vasculature, thereby applying torsional stress bothto the stent and to the stent's retention members that are coupled tothe recesses 36. Such torsional stress may increase friction between theretention members of the stent and the recesses 36, such that, when thedistal sheath 22 uncovers the compartment 28 to deploy the valve, theforce from the bias of the stent to radially expand may not besufficient to free all of the retention members from the recesses. Theability of the energy storage elements described herein to store energymay allow the retainer provide a radially-outward force when the distalsheath 22 uncovers the valve in the compartment 28, thereby aidingrelease of the valve from the compartment by helping to overcomefriction between the retention members of the stent and the recesses. Itwill be appreciated that the various springs described herein can bemade of any conventional material, including metal, memory metal,plastic, and the like.

FIGS. 8A and 8B show further alternate embodiments of the retainer 30described above in connection with the embodiments of FIGS. 1A through7D. The retainer embodiments shown in FIGS. 8A and 8B and describedbelow may be used with any of the delivery devices described herein.

As shown in FIG. 8A, the retainer 30 a has recesses 36 a withprotuberances 37 a projecting towards one another to define a narrowedneck 38 a that limits the longitudinal movement of a correspondingretention member 4 of a heart valve stent toward a retention edge 34 ofthe retainer. The recesses 36 a are configured to produce a surfacecontact between the retention member 4 and the protuberances 37 a when acompressive, tensile, or torsional load is applied to the retentionmember.

As shown in FIG. 8B, the retainer 30 b has recesses 36 b withprotuberances 37 b projecting towards one another to define a narrowedneck 38 b. The retention members 4 and the recesses 36 b are preferablyconfigured to produce as small of a surface contact as possible betweenthe retention member 4 and an angled surface 39 or wall of the recess 36when a compressive, tensile, or torsional load is applied to theretention member. Most preferred is a surface contact between theretention member 4 and an angled surface 39 of the recess that is closeto a single point of contact between the retention member and the angledsurface at either side of the recess, which is referred to herein as“point contact” between the two surfaces.

In one example, such a point contact may be achieved by having an angleA between the longitudinal axis L of the retainer 30 and an angledsurface 39 of the recess that is greater than an angle B between thelongitudinal axis of the recess and a corresponding portion of theretention member 4. In other examples, any combination of contours ofthe retention member 4 and the angled surface 39 of the recess 36 may beused that minimizes the contact surfaces between the angled surface andthe retention member when a compressive, tensile, or torsional load isapplied to the retention member.

Although three recesses 36 spaced 120° apart about the circumference ofthe retainer are shown FIGS. 7B and 7C, the device 10 (and all of theother retainers disclosed herein) may have any number of recesses,including for example, one, two, four, six, eight, or nine recesses.Further, each recess 36 d (and all of the other recesses disclosedherein) may have only a single protuberance defining the neck, or anynumber of protuberances greater than two. Although three retentionmembers 4 are described as being engaged in the three respectiverecesses 36 in the figures shown, the retainers described herein may beused with stents 1 having any number of retention members 4, includingfor example, one, two, four, six, or eight retention members.

Although the various retainer embodiments have been described here inconnection with retaining for deployment a prosthetic valve having acollapsible stent structure, all of the retainer embodiments may be usedfor other purposes. In particular, the various embodiments of retainersmay be used to retain conventional collapsible stents that do notcontain a valve.

Although the invention herein has been described with reference toparticular embodiments in which the annulus end of a prosthetic valve isdeployed first, it is to be understood that the invention contemplatesembodiments in which the aortic end of a valve is deployed first. Insuch embodiments (not shown), retention members may protrude from theannulus end of the stent portion of the valve for engagement with aretainer of the delivery device, such that the aortic end of the stentis remote from the retainer and may be unsheathed first. In still otherembodiments (not shown), retention members may protrude from both theaortic and the annulus ends of the stent portion of the valve forengagement with a retainer.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

1. A delivery device for an implantable medical device having aretention member at an end thereof, the delivery device comprising: ashaft extending in a longitudinal direction and defining a longitudinalaxis; an elongated sheath surrounding a longitudinal portion of theshaft, the sheath being slidable relative to the shaft in thelongitudinal direction; a compartment defined inside the sheath andadapted to receive the medical device in an assembled condition; aretainer positioned at one end of the compartment, the retainerincluding a recess adapted to receive the retention member of themedical device in the assembled condition; and an energy storage elementconfigured to be radially compressed by the medical device when theelongated sheath covers the compartment containing the medical device,the energy storage element being a recess insert, the recess insertoverlying a bottom surface of the recess.
 2. The delivery device ofclaim 1, wherein the recess insert is a pad of elastomeric material. 3.The delivery device of claim 2, wherein the elastomeric material isselected from the group consisting of silicone, urethane, nylon, pebax,santoprene, butyl, neoprene, and combinations thereof.
 4. The deliverydevice of claim 2, wherein the recess insert has a planar upper surfacethat has a contour that conforms to a contour of the bottom surface ofthe recess.
 5. The delivery device of claim 2, wherein the recess inserthas a planar upper surface that is convexly curved in a circumferentialdirection around the longitudinal axis of the shaft, such that the uppersurface of the elastomeric insert forms a portion of a cylinder.
 6. Thedelivery device of claim 2, wherein the recess insert is attached to thebottom surface of the recess by interlocking of a prong into a cavityextending into the retainer from the bottom surface of the recess. 7.The delivery device of claim 1, wherein the recess insert is a layer ofelastomeric material that is conformally deposited within the recess. 8.The delivery device of claim 7, wherein the layer of elastomericmaterial completely lines the recess, such that the layer of elastomericmaterial extends across the bottom surface and sidewalls of the recessthat extend from the bottom surface in a radial directions that aretransverse to the bottom surface.
 9. The delivery device of claim 1,wherein the recess insert is a spring.
 10. The delivery device of claim9, wherein the recess insert is a leaf spring that is attached to thebottom surface or one or more sidewalls of the recess, the leaf springbeing biased to exert a force in a radial direction transverse to thebottom surface when the retention member is pushed against the leafspring in a direction opposite the radial direction.
 11. The deliverydevice of claim 9, wherein the recess insert is a coil spring that isattached to the bottom surface, one or more sidewalls of the recess, ora surface of a cavity extending below the bottom surface, the coilspring being biased to exert a force in a radial direction transverse tothe bottom surface when the retention member is pushed against the coilspring in a direction opposite the radial direction.
 12. The deliverydevice of claim 1, wherein the retention member is one of a plurality ofretention members at the end of the delivery device, the recess is oneof a plurality of recesses in the retainer, each of the recesses beingadapted to receive a corresponding one of the retention members of themedical device in the assembled condition, and the recess insert is oneof a plurality of recess inserts each disposed in a corresponding one ofthe recesses.
 13. A method of prosthetic valve delivery, comprising:providing an expandable prosthetic valve having a retention member at anend thereof; loading the valve into a compartment of a delivery device,the delivery device including a shaft, an elongated sheath surrounding alongitudinal portion of the shaft and slidable in longitudinaldirections relative to the shaft, an energy storage element, a retainerpositioned at one end of the compartment, and a recess in the retainer,the valve being loaded into the compartment with the retention memberpositioned in the recess and with the valve overlying at least a portionof the energy storage element; sliding the sheath in a first one of thelongitudinal directions over the valve to radially compress the energystorage element and to hold the energy storage element in a compressedcondition, the energy storage element being a recess insert, the recessinsert overlying a bottom surface of the recess; inserting the deliverydevice in a patient to position the valve at a target location; andsliding the sheath in a second one of the longitudinal directions touncover the valve, wherein the energy storage element is released fromthe compressed condition and radially expands to impart an outwardradial force to the valve.
 14. The method of claim 13, wherein therecess insert is a pad of elastomeric material.
 15. The method of claim14, wherein the recess insert has a planar upper surface that has acontour that conforms to a contour of the bottom surface of the recess.16. The method of claim 14, wherein the recess insert is attached to thebottom surface of the recess by interlocking of a prong into a cavityextending into the retainer from the bottom surface of the recess. 17.The delivery device of claim 13, wherein the recess insert is a layer ofelastomeric material that is conformally deposited within the recess.18. The method of claim 13, wherein the recess insert is a spring. 19.The method of claim 18, wherein the recess insert is a leaf spring thatis attached to the bottom surface or one or more sidewalls of therecess, the leaf spring being biased to exert a force in a radialdirection transverse to the bottom surface when the retention member ispushed against the leaf spring in a direction opposite the radialdirection.
 20. The method of claim 18, wherein the recess insert is acoil spring that is attached to the bottom surface, one or moresidewalls of the recess, or a surface of a cavity extending below thebottom surface, the coil spring being biased to exert a force in aradial direction transverse to the bottom surface when the retentionmember is pushed against the coil spring in a direction opposite theradial direction.